Headbox for a machine for producing a fibrous material web, in particular a paper or cardboard web

ABSTRACT

A headbox for a machine for producing a fibrous material web, in particular a paper or cardboard web, includes: a central assembly preferably forming the carrier elements of a turbulence generator, said assembly having a table leaf on the bottom side; and a headbox nozzle adjoining directly downstream in the machine running direction and extending in the machine transverse direction, said nozzle comprising at least one lower and one upper continuous nozzle wall extending over the machine width. The lower nozzle wall of the headbox nozzle of the headbox includes a lower lip plate, in particular a lower lip carrier plate, which is connected, in particular welded, to the table leaf of the central assembly by means of ribs extending in the machine running direction and spaced apart in the machine transverse direction. The ribs are designed in an elastic or pliable manner in the machine transverse direction.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a continuation of PCT application No. PCT/EP2010/056519,entitled “HEADBOX FOR A MACHINE FOR PRODUCING A FIBROUS MATERIAL WEB, INPARTICULAR A PAPER OR CARDBOARD WEB”, filed May 12, 2010, which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a headbox for a machine for producing a fibrousweb, in particular a paper or cardboard web, comprising a centralassembly preferably forming the carrier elements of a turbulencegenerator; said assembly having a table leaf on the bottom side andfurther comprising a headbox nozzle adjoining directly downstream inmachine direction and extending in transverse machine direction; saidnozzle comprising at least one lower and one upper continuous nozzlewall extending across the machine width.

2. Description of the Related Art

A headbox of this type is known for example from publications DE 198 45722 A1 and EP 0 997 578 A1 and EP 1 342 835 A2.

The headbox discussed in the first publication has a lower nozzle wallmounted to slide on a support component of a base plate or table leafand movable relative thereto in longitudinal flow direction. The lowernozzle wall is hereby movable in the desired direction through at leastone for example mechanical, hydraulic and/or pneumatic adjustmentdevice. This adjustment device engages on the support component and onthe lower nozzle wall, and the support component extends over asubstantial length of the lower nozzle wall.

The headbox of the second referred to publication comprises a headboxnozzle having a lower nozzle wall and an upper nozzle wall. The uppernozzle wall is pivoted by means of a hinge around an axis extending incross machine direction. In contrast, the lower nozzle wall is movablein machine direction on a stationary base plate or table leaf.

These two illustrated headboxes represent a first headbox type with anopen turbulence generator which in each instance is mounted stationary,in particular bolted onto the table top and which represents one centralassembly.

On a second headbox type the turbulence generator forming the centralassembly is a closed design, in other words, it is an enclosed box-typeturbulence generator. With a headbox of this type which is known forexample from publication EP 1 653 000 A1 at least one heating chamberthrough which at least one fluid flows is provided. The sealedturbulence generator hereby assumes the function of a heat exchangerwhich takes the heat from the fibrous stock suspension fed to it andtransfers it to the at least one fluid. Through this at least oneheating chamber differential heating, or heating at different speeds offunctionally important components of the headbox are equalized.

Since on a headbox of the first type this heat exchanger system is notprovided, or respectively cannot be realized, a differential thermalexpansion of the functionally important components cannot be avoided, inparticular during the start-up process of the headbox with a fibrousstock suspension at a temperature of up to 70° C. The components whichare in contact with the stock, for example the two machine-wide nozzlewalls and the turbulence pipes, expand faster than components which arenot in contact with the stock, for example the cover plate of theturbulence generator and the table leaf. Due to the rigid connections ofthe components in contact with the stock and those not in contact withthe stock, generally high tensions, in particular bending stresses andextensive deformations occur on the headbox, and in turn also on theheadbox nozzle. These extensive deformations lead to disadvantageousoperating conditions of the headbox which are well known to the expert,for example a different gap width of the headbox nozzle in cross machinedirection and therefore also to distinctly negative qualitycharacteristics in the fibrous web which is to be produced. Moreover,the increased tensions, in particular the bending stresses, can alsolead to a structural failure of individual components, for example ofthe welding joints.

In order to reduce or avoid the cited disadvantages, arrangements havealready been made to provide the box-type components of the headbox ontheir inside circumference and preferably opposite the box walls whichare contacted by the fibrous stock suspension with heating pockets whichare flushed with a temperature moderating liquid. Heating pockets ofthis type are known for example from the German disclosure document DE41 06 763 A1. In order to achieve an isothermal headbox up to sixheating pockets were placed for example at different locations.

The use of heating pockets however always represents a compromise sincethere are always warm and cold locations and they conditionally requiremany additional parts which—in regard to the use of a temperingfluid—enhance the risk of leakage. Moreover, the internal rib structureis expensive and the heating and distribution system for the temperingfluid is cost intensive, both in regard to purchase as well asoperation. Also, the determination of the location and the size of theheating pocket is dependent upon the components used so that a greaterrange of variants occurs. The expensive foundation can also not beneglected since even with a non-operational heating system the occurringand not insignificant deformation forces must be absorbed.

It is therefore the objective of the current invention, and what isneeded in the art is, to improve a headbox of the type described at thebeginning so that the known disadvantages of the current state of theart are most extensively, preferably completely, avoided. The headboxshould in particular always ensure an as parallel and straight outletgap on the headbox nozzle as possible with an as cost-effective aspossible construction, simple handling and minimum maintenanceexpenditure.

An as uniform as possible impingement line of the fibrous stocksuspension jet coming from the headbox nozzle onto the at least one wirein the wire section should thereby also be achievable without problems.

SUMMARY OF THE INVENTION

This objective is met in, and the present invention provides, a headboxof the type described at the beginning in that the lower nozzle wall ofthe headbox nozzle comprises a lower lip plate, in particular a lowerlip support plate which is connected, in particular welded, to the tableleaf of the central assembly by means of a plurality of ribs extendingin machine direction and spaced apart in cross machine direction, andthat the ribs are designed to be pliable or flexible in cross machinedirection.

The objective of the invention is hereby completely met.

Through the new design of the connecting region between lower lip plate,lower lip support plate of the lower nozzle wall of the headbox nozzle,and the table leaf of the central assembly, sufficient slidingresilience is ensured in order to compensate for occurring tensions, inparticular bending stresses and deformations. The redesign of thiscompensating connecting region has no structural-mechanicaldisadvantages compared to the current state of the art. The flexuralstrength in regard to a possible expansion of the headbox nozzle is thesame, since the geometric moment of inertia of the ribs which aredesigned to be pliable and flexible only in cross machine direction isnot being reduced.

The required sliding resilience of the entire table construction of thecentral assembly is comprehensively provided in order to compensate forinfluences such as, for example, different thermal expansions in crossmachine direction.

Moreover, this new design does not need to provide explicit and possiblycost-intensive reinforcement in cross machine direction.

Also, the material of the ribs which are designed to be pliable andflexible in cross machine direction only can be varied. One the one handit can be a simple structural steel, on the other hand also a stainlesssteel.

The individual ribs preferably extend at least partially generallyvertically, that is perpendicular to the lower nozzle wall of theheadbox nozzle and the table leaf of the central assembly. Thisarrangement provides an optimum opportunity to absorb and transmit theforces prevailing during operation of the headbox.

The individual ribs moreover have preferably a rib thickness in therange of 10 to 75 mm, preferably 15 to 60 mm, in particular 20 to 50 mm.Due to these relatively small rib thicknesses the tensions, inparticular the bending stresses in the joints, in particular in the weldseams, are also minimized. In principle, the smallest possible ribthicknesses are to be strived for, whereby they are however essentiallydependent upon the machine speed of the machine for the production ofthe fibrous web and are therefore directly dependent upon the nozzlepressure prevailing in the headbox nozzle.

The individual ribs moreover preferably have a rib separation in therange of 100 to 500 mm, preferably of 125 mm to 400 mm, in particular150 to 250 mm. This arrangement provides again an optimum opportunity toabsorb and transmit the forces prevailing during operation of theheadbox.

In principle, a reduction in the rib separation is preferable to anincrease in the rib thicknesses. Therefore, a combination of 20 mm ribthickness and 200 mm rib separation is preferable for example to thecombination of 40 mm rib thickness and 400 mm rib separation.

Moreover, the table leaf of the central assembly—in the region facingthe lower lip plate, in particular the lower lip support plate of thelower nozzle wall of the headbox nozzle—is preferably provided with achamfer forming a first bevel, whereby the chamfer can have a length ofat least 25 mm, preferably at least 40 mm, in particular at least 50 mm.The table leaf of the central assembly can therefore receive agenerously dimensioned slant at its rear and upper end, viewed inmachine direction.

Also the lower lip plate, in particular the lower lip support plate ofthe lower nozzle wall of the headbox nozzle—in the region facing thetable leaf of the central assembly—is preferably provided with a chamferforming a second bevel, whereby the chamfer has preferably a length ofat least 25 mm, preferably at least 40 mm, in particular at least 50 mm.The lower lip plate, in particular the lower lip support plate of thelower nozzle wall of the headbox nozzle can therefore receive agenerously dimensioned slant at its frond and lower end, viewed inmachine direction.

These two bevels in the form of chamfers increase the minimum rib heightin the addressed connecting region by a multiple. The connection betweenlower lip plate, in particular the lower lip support plate of the lowernozzle wall of the headbox and the table leaf of the central assemblycan thereby be designed flexible and direct.

Moreover, bevels formed by the two chamfers preferably encompasstogether an angle of 0 to 45°, preferably 5 to 30°, in particular 10 to20°. The two chamfers may progress parallel to each other, or divergent.This allows for simpler insertion of ribs during the production process.

The individual ribs which connect the lower lip plate, in particular thelower lip support plate of the lower nozzle wall of the headbox nozzlewith the table leaf of the central assembly are preferably structured tofill in, in the regions of the two chamfers in order to thereby maintainthe necessary flexural strength of the table leaf of the centralassembly.

Moreover, the table leaf of the central assembly and the lower lipplate, in particular the lower lip support plate of the lower nozzlewall of the headbox nozzle preferably have a perpendicular distance inthe range of 10 to 100 mm, preferably 20 to 80 mm, in particular 25 to65 mm, whereby the perpendicular distance between the theoretic insideextension of the table leaf of the central assembly and the theoreticcorner edge of the lower lip plate, in particular the lower lip supportplate of the lower nozzle wall of the headbox nozzle is measured. Thiscauses a largely inflexible, rigid and indirect connection between thelower lip plate, in particular the lower lip support plate of the lowernozzle wall of the headbox nozzle and the table leaf of the centralassembly. A certain varying deformation, in particular through thermalheating, can be compensated by this design. Greater deformations (inparticular with large outlet widths) can however be absorbed only withinlimits, since the deformations may get relatively large in the outerregions (edges).

The individual ribs are furthermore provided with a compensating gap inthe region facing the front side of the table leaf, whereby therespective compensating gap has a height in the range of 2 to 15 mm,preferably 3 to 12 mm, in particular 5 to 10 mm. This ensures a definedcontact with the adjacent components.

Moreover, the joints between the table leaf of the central assembly andthe individual ribs and/or between the lower lip plate, in particularthe lower lip support plate of the lower nozzle wall of the headboxnozzle and the individual ribs which are in the form of welding seamshave preferably a welding seam thickness in the range of 3 to 15 mm,preferably 4 to 12 mm, in particular 5 to 10 mm. Ideally, the weldingseams are to be in the form of fillet welds.

Even with larger outlet widths, the tensions, in particular the bendingstresses and consequently the deformations in the ribs and welded seamsare kept in an acceptable range by this means.

The minimum height of the individual ribs between the table leaf of thecentral assembly and the lower lip plate, in particular the lower lipsupport plate of the lower nozzle wall of the headbox nozzle preferablyassumes a value in the range of 1.5 to 4, preferably 2 to 3 times theperpendicular distance between the table leaf of the central assemblyand the lower lip plate, in particular the lower lip support plate ofthe lower nozzle wall of the headbox nozzle. This again provides asubstantial contribution toward maintaining the essential flexuralstrength of the table leaf of the central assembly.

The individual ribs respectively are preferably connected directly orindirectly, in particular by at least one hinged joint and a base plateand/or a pedestal with the bed plate. This type of connection allows fora simple and rapid adjustment, in particular pivoting of the entireheadbox.

Moreover, the lower lip support plate of the lower nozzle wall of theheadbox nozzle is equipped preferably on the upper and outlet side witha preferably positionable lower lip. This creates a practicablereplacement possibility and noticeably improves production of the lowernozzle wall.

The inventive headbox can also be used very advantageously in a machinefor the production of a fibrous web from at least one fibrous stocksuspension. Thereby, the preferably dilution water controlled headboxcan be designed as a single layer or multi-layer headbox and the fibrousweb may be a paper, cardboard or tissue web.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention,and the manner of attaining them, will become more apparent and theinvention will be better understood by reference to the followingdescription of embodiments of the invention taken in conjunction withthe accompanying drawings, wherein:

FIG. 1 a schematic and partially cut side view of a headbox according tothe current state of the art;

FIG. 2 a schematic partial sectional side view of a preferred designform of a headbox according to the invention;

FIG. 3 a schematic front view of the inventive headbox according to FIG.2;

FIG. 4 a schematic perspective partial depiction of the headboxaccording to FIG. 2;

FIGS. 5 and 6 two schematic perspective partial views of a rib of theinventive headbox in FIG. 2; and

FIG. 7 a schematic sectional side view of the inventive headbox which ispartially sectionally depicted in FIG. 2.

Corresponding reference characters indicate corresponding partsthroughout the several views. The exemplifications set out hereinillustrate one embodiment of the invention, and such exemplificationsare not to be construed as limiting the scope of the invention in anymanner.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a purely schematic illustration of a headbox 1 which is knownfrom the current state of the art for a Fourdrinier-former in a machineto produce a fibrous web. The fibrous web may in particular be in theembodiment of a paper, cardboard or tissue web.

In the current example, a central assembly 2 of known headbox 1comprises a lower arm formed by a table leaf 3, an upper arm progressingpreferably at least partially essentially parallel thereto and formed bya cover plate 4, an upstream first central component 5, and a secondcentral component positioned further back or downstream, viewed inmachine direction L (arrow). Cover plate 4 and the two centralcomponents 5, 6 which are located between said cover plate 4 and tableleaf 3 hereby form preferably support elements of a turbulence generator7.

Central assembly 2 which, in the current design example is in theembodiment of a turbulence generator 7, is equipped with several stepdiffusors or with continuous turbulence pipes.

At least one fibrous stock suspension 9 is fed directly to centralassembly 2, for example through a lateral distribution manifold 8.Feeding the at least one fibrous stock suspension 9 may also occurindirectly, for example through a preferably machine-wide intermediatechamber.

Known headbox 1 further includes headbox nozzle 10 extending in crossmachine direction Q (arrow) across machine width B (arrow), having alower and an upper nozzle wall 11 or respectively 12, extendingrespectively across machine width B (arrow). In the current designexample, upper nozzle wall 12 can be pivoted by means of a hinge 13around an axis A (swivel axis) (double arrow S) extending in crossmachine direction Q (arrow). Moreover, in the current example the lowernozzle wall 11 which is in the embodiment of simple lower lip plate 14is movable (double arrow V) in machine direction L (arrow) on stationarytable leaf 3. Lower lip plate 14 and lower nozzle wall 11 of headboxnozzle 10 represent one assembly.

Headbox nozzle 10 is located immediately following central assembly 2 inmachine direction L (arrow).

The flow is directed to an outlet gap 16 via lower nozzle wall 11 andupper nozzle wall 12, as well as lateral limits 15, for example sideplates or similar devices. The machine-wide stock jet emerging fromoutlet gap 16 is admitted onto a continuous revolving wire 18 in theregion of a breast roll 17.

The stationary table leaf 3 for lower nozzle wall 11 or a stationarynozzle wall is supported on a bed plate 20 by several support elements19 which are distributed across the machine width B (arrow). Supportelements 19 are designed to be pliable or flexible in cross machinedirection Q (arrow).

Individual support elements 19 extend vertically, that is perpendicularto lower nozzle wall 12 or respectively to table leaf 3. In the currentexample these support elements 19 are in the embodiment of plates,located parallel to machine direction L (arrow). They can however alsobe in the form of stud bolts or similar devices.

In the current design example the support elements 19 are connected withbed plate 20 through a pedestal 21, consisting for example of concrete.In principle, these support elements 19 can however also be connecteddirectly with base plate 20. At the other end, support elements 19 arerespectively connected with table leaf 3. In the case of a non-movablelower nozzle wall which, in other words is a single component togetherwith the table leaf, the support elements would be connected with thenon-movable lower nozzle wall.

Upper nozzle wall 12 which is pivoted by means of hinge 13 around axis Ais connected with a cross bar 23 which is located above axis A by meansof several separate support elements 22 which are distributed acrossmachine width B (arrow). Support elements 22 are again designed to bepliable and flexible in cross machine direction Q (arrow).

One or several lifting elements 24 are hinged on the one hand on centralassembly 2 and on the other hand on cross bar 23 by means of articulatedaxis 25 or respectively 26. Through these lifting elements 24 uppernozzle wall 12 can thereby be pivoted around axis A in direction ofdouble arrow S. The lifting elements may for example be threadedspindles, hydraulic cylinders and/or similar devices.

Cross bar 23 may for example be in the embodiment of an upright sheetmetal or a hollow beam.

On the back end of cover plate 4 of central assembly 2, viewed inmachine direction L (arrow), a continuous hinged support 27 of hinge 13extending in cross machine direction Q (arrow) is provided into which acounter element 28 which is provided on upper nozzle wall 12 engages.

Known headbox 1 illustrated in FIG. 1 is oriented substantiallyhorizontally. It can however also be oriented with its outlet gap 16slanting upwards into an inlet gap formed between two wires.

FIG. 2 shows a schematic cut partial side view of a preferred designform of a headbox according to the invention. In regard to the generalstructural design of the illustrated inventive headbox 1 we refer you tothe design and description of known headbox 1 illustrated in FIG. 1.

Central assembly 2 of inventive headbox 1 again includes a table leaf 3,a cover plate 4 preferably at least substantially parallel thereto, anupstream first central component 5 and a second central component 6,located further back or downstream, viewed in machine direction L(arrow). Cover plate 4 and the two central components 5, 6 which arelocated between said cover plate 4 and table leaf 3 hereby formpreferably support elements of a turbulence generator 7.

Lower nozzle wall 11 of headbox nozzle 10 however, comprises a lower lipplate 14, in particular a lower lip support plate 14.1, which isconnected, in particular welded to, table leaf 3 of central assembly 2by means of a plurality of ribs 29 extending in machine direction L(arrow) and spaced apart in cross machine direction Q (arrow). Ribs 29are designed to be pliable or flexible in cross machine direction Q(arrow).

The individual ribs 29 extend at least partially generally vertically,that is perpendicular to lower nozzle wall 11 of headbox nozzle 10 andtable leaf 3 of central assembly 2 (see FIG. 3).

Moreover, table leaf 3 of central assembly 2—in region 30 facing lowerlip plate 14, in particular lower lip support plate 14.1 of lower nozzlewall H of headbox nozzle 10—is provided with a chamfer 31 forming afirst bevel 32, whereby chamfer 31 preferably has a length L.31 of atleast 25 mm, preferably at least 40 mm, in particular at least 50 mm.

Also lower lip plate 14, in particular lower lip support plate 14.1 oflower nozzle wall 11 of headbox nozzle 10—in region 33 facing table leaf3 of central assembly 2—is provided with a chamfer 34 forming a secondbevel 35, whereby chamfer 34 has preferably a length L.34 of at least 25mm, preferably at least 40 mm, in particular at least 50 mm.

Bevels 32 or 35 respectively formed by the two chamfers 31 or 34respectively preferably encompass an angle of 0 to 45°, preferably 5 to30°, in particular 10 to 20°. At an angle W of 0° they progress parallelto each other, at an angle W of 45° they progress below a half rightangle to each other.

Furthermore, individual ribs 29 which connect lower lip plate 14, inparticular lower lip support plate 14.1 of lower nozzle wall 11 ofheadbox nozzle 10 with table leaf 3 of central assembly 2 are preferablystructured to fill in, in the regions of the two chamfers 31 or 34respectively.

Table leaf 3 of central assembly 2 and lower lip plate 14, in particularlower lip support plate 14.1 of lower nozzle wall 11 of headbox nozzle10 have a perpendicular distance C in the range of 10 to 100 mm,preferably 20 to 80 mm, in particular 25 to 65 mm. The perpendiculardistance C is hereby measured per definition between the theoreticinside extension 36 of table leaf 3 of central assembly 2 and theoreticcorner edge 37 of lower lip plate 14, in particular lower lip supportplate 14.1 of lower nozzle wall 11 of headbox nozzle 10.

Moreover, the individual ribs 29 are provided with a compensating gap 40in region 39 facing front side 38 of table leaf 3, whereby therespective compensating gap 40 has a compensating gap height H.40 in therange of 2 to 15 mm, preferably 3 to 12 mm, in particular 5 to 10 mm.

Minimum height H.29 of individual ribs 29 between table leaf 3 ofcentral assembly 2 and lower lip plate 14, in particular lower lipsupport plate 14.1 of lower nozzle wall 11 of headbox nozzle 10 assumesa value in the range of 1.5 to 4, preferably 2 to 3 times theperpendicular distance C between table leaf 3 of central assembly 2 andlower lip plate 14, in particular lower lip support plate 14.1 of lowernozzle wall 11 of headbox nozzle 10.

Lower lip support plate 14 of lower nozzle wall 11 of headbox nozzle 10is equipped on the upper and outlet side with a preferably positionablelower lip 43.

FIG. 3 shows a schematic front view of headbox 1 according to theinvention shown in FIG. 2.

Individual ribs 29 have a rib thickness D.29 in the range of 10 to 75mm, preferably 15 to 60 mm, in particular 20 to 50 mm, and a ribseparation T.29 in the range of 100 to 500 mm, preferably of 125 mm to400 mm, in particular 150 to 250 mm.

Joints 41 which are in the form of welding seams 42 between table leaf 3of central assembly 2 and individual ribs 29 and/or between lower lipplate 14, in particular lower lip support plate 14.1 of lower nozzlewall 11 of headbox nozzle 10 and individual ribs 29 have a welding seamthickness D.42 in the range of 3 to 15 mm, preferably 4 to 12 mm, inparticular 5 to 10 mm. For reasons of comprehension, welding seams 42are shown over-dimensioned only on center rib 29.

FIG. 4 shows a schematic perspective partial illustration of inventiveheadbox 1 shown in FIG. 2.

Central assembly 2 of inventive headbox 1 comprises a table leaf 3, acover plate 4 preferably at least substantially parallel thereto, anupstream—however not illustrated—first central component and a secondcentral component 6, located further back or downstream, viewed inmachine direction L (arrow). Cover plate 4 and the two centralcomponents which are located between said cover plate 4 and table leaf 3hereby form preferably again support elements of a turbulence generator7.

Turbulence generator 7 is equipped with several step diffusors or withcontinuous turbulence pipes.

Lower nozzle wall H of headbox nozzle 10 comprises a lower lip plate 14,in particular a lower lip support plate 14.1 which is connected, inparticular welded to table leaf 3 of central assembly 2 by means of aplurality of ribs 29 extending in machine direction L (arrow) and spacedapart in cross machine direction Q (arrow). Ribs 29 are designed to bepliable or flexible in cross machine direction Q (arrow).

The individual ribs 29 extend at least partially generally vertically,that is perpendicular to lower nozzle wall 11 of headbox nozzle 10 andtable leaf 3 of central assembly 2 (see FIG. 3).

Table leaf 3 of central assembly 2—in region 30 facing lower lip plate14, in particular lower lip support plate 14.1 of lower nozzle wall 11of headbox nozzle 10—is provided with a chamfer 31 forming a first bevel32. Moreover, lower lip plate 14, in particular lower lip support plate14.1 of lower nozzle wall 11 of headbox nozzle 10 is provided with achamfer 34 forming a second bevel 35 in region 33 facing table leaf 3 ofcentral assembly 2.

FIGS. 5 and 6 show two schematic partial depictions of a rib 29 ofinventive headbox 1 shown in FIG. 2.

Respective lower nozzle wall 11 of headbox nozzle 10 comprises aseparate lower lip plate 14, in particular a separate lower lip supportplate 14.1 which is connected, in particular welded, to table leaf 3 ofcentral assembly 2 by means of a plurality of ribs 29 extending inmachine direction L (arrow) and spaced apart in cross machine directionQ (arrow). Ribs 29 are designed to be pliable or flexible in crossmachine direction Q (arrow).

The individual ribs 29 extend at least partially generally vertically,that is perpendicular to lower nozzle wall 11 of headbox nozzle 10 andtable leaf 3 central assembly 2 (see FIG. 3).

The individual ribs 29 have a rib thickness D.29 in the range of 10 to75 mm, preferably 15 to 60 mm, in particular 20 to 50 mm (see FIG. 5).

Individual ribs 29 are furthermore provided with a compensating gap 40in region 39 facing front side 38 of respective table leaf 3.

Table leaf 3 of the respective central assembly 2—in region 30 facinglower lip plate 14, in particular lower lip support plate 14.1 of lowernozzle wall 11 of headbox nozzle 10—is provided with a chamfer 31forming a first bevel 32. Moreover, lower lip plate 14, in particularlower lip support plate 14.1 of lower nozzle wall 11 of headbox nozzle10 is provided with a chamfer 34 forming a second bevel 35 in region 33facing table leaf 3 of central assembly 2.

The respective lower lip support plate 14 of lower nozzle wall 11 ofindividual headbox nozzle 10 is equipped on the upper and outlet sidewith a preferably positionable lower lip 43.

FIG. 7 is a schematic sectional side view of inventive headbox 1 whichis depicted in partial sectional view in FIG. 2.

In regard to the general structural design of the illustrated inventiveheadbox 1 we refer you to the design and description of known headbox 1illustrated in FIG. 1. In regard to the inventive design of headbox 1 werefer you to the design and description of the inventive headbox 1illustrated in FIG. 2.

It can be clearly seen that individual ribs 29 of inventive headbox 1are connected indirectly with bed plate 20. The indirect connectionoccurs on the inlet side by means of at least one machine-wide hinge 44and one pedestal 21 and on the outlet side by means of several liftingelements 45 arranged at a distance from each other and which are onlyindicated here. Lifting elements 45 may for example be threadedspindles, hydraulic cylinders and/or similar devices. Inventive headbox1 is therefore adjustable in its position.

Obviously, the connection may also be implemented directly by means ofat least a hinged joint and a base plate and/or a pedestal. A directconnection of the inventive headbox 1 with bed plate 20 is alsopossible.

Inventive headbox 1 illustrated and accordingly described in FIGS. 2through 7 can also be used very advantageously in a machine for theproduction of a fibrous web, in particular a paper, cardboard or tissueweb.

In summary it must be stated that the invention creates a headbox of thetype described at the beginning, whereby the known disadvantages of thecurrent state of the art are most extensively, preferably completelyavoided. The headbox should in particular always ensure an as paralleland straight outlet gap on the headbox nozzle as possible with an ascost-effective as possible construction, simple handling and minimummaintenance expenditure. An as uniform as possible impingement line ofthe fibrous stock suspension jet coming from the headbox nozzle onto theat least one wire in the wire section should thereby also be achievablewithout problems.

While this invention has been described with respect to at least oneembodiment, the present invention can be further modified within thespirit and scope of this disclosure. This application is thereforeintended to cover any variations, uses, or adaptations of the inventionusing its general principles. Further, this application is intended tocover such departures from the present disclosure as come within knownor customary practice in the art to which this invention pertains andwhich fall within the limits of the appended claims.

COMPONENT IDENTIFICATION LIST

-   -   1 Headbox    -   2 Central assembly    -   3 Table leaf (lower arm)    -   4 Cover plate (upper arm)    -   5 First central component (support element)    -   6 Second central component (support element)    -   7 Turbulence generator    -   8 Lateral manifold    -   9 Fibrous stock suspension    -   10 Headbox nozzle    -   11 Lower nozzle wall    -   12 Upper nozzle wall    -   13 Hinge    -   14 Lower lip plate    -   14.1 Lower lip support plate    -   15 Lateral limits    -   16 Outlet gap    -   17 Breast roll    -   18 Wire    -   19 Support element    -   20 Bed plate    -   21 Pedestal    -   22 Support element    -   23 Cross bar    -   24 Lifting element    -   25 Articulated axis    -   26 Articulated axis    -   27 Support hinge    -   28 Counter element    -   29 Rib    -   30 Region    -   31 Chamfer    -   32 First bevel    -   33 Region    -   34 Chamfer    -   35 Second bevel    -   36 Extension    -   37 Corner edge    -   38 Front side    -   39 Region    -   40 Compensating gap    -   41 Joint    -   42 Welded seam    -   43 Lower lip    -   44 Hinge, hinged connection    -   45 Lifting element    -   A Axis (Swivel axis)    -   B Machine width (arrow)    -   C Perpendicular distance    -   D.29 Rib thickness    -   D.42 Welded seam thickness    -   H.29 Minimum height    -   H.40 Gap height    -   L Machine direction (arrow, double arrow)    -   L.31 Chamfer length    -   L.34 Chamfer length    -   Q Cross machine direction (arrow)    -   S Double arrow (pivotability)    -   T.29 Rib separation    -   Double arrow (movability)    -   W Angle

What is claimed is:
 1. A headbox for a machine for producing a web offibrous material, the web being one of a paper web and a cardboard web,said headbox comprising: a central assembly including a bottom side andhaving a table leaf on said bottom side; a plurality of ribs; and aheadbox nozzle adjoining said central assembly directly downstream in amachine direction and extending in a cross machine direction, saidheadbox nozzle including at least one continuous lower nozzle wall andat least one continuous upper nozzle wall extending across a machinewidth, said at least one continuous lower nozzle wall of said headboxnozzle including a lower lip plate which is connected to said table leafof said central assembly by way of said plurality of ribs extending insaid machine direction and spaced apart in said cross machine direction,said plurality of ribs being one of pliable and flexible in said crossmachine direction.
 2. The headbox according to claim 1, furtherincluding a turbulence generator, said central assembly forming aplurality of carrier elements of said turbulence generator.
 3. Theheadbox according to claim 1, wherein said lower lip plate is welded tosaid table leaf.
 4. The headbox according to claim 1, wherein said lowerlip plate is a lower lip support plate.
 5. The headbox according toclaim 4, wherein said lower lip support plate of said at least onecontinuous lower nozzle wall of said headbox nozzle includes an upperand outlet side, said lower lip support plate being equipped on saidupper and outlet side with a lower lip.
 6. The headbox according toclaim 5, wherein said lower lip is positionable.
 7. The headboxaccording to claim 1, wherein individual ones of said plurality of ribsextend at least partially generally vertically and thereby perpendicularto said at least one continuous lower nozzle wall of said headbox nozzleand said table leaf of said central assembly.
 8. The headbox accordingto claim 1, wherein individual ones of said plurality of ribs have a ribthickness in a range of 10 mm to 75 mm.
 9. The headbox according toclaim 1, wherein individual ones of said plurality of ribs have a ribthickness in a range of 15 mm to 60 mm.
 10. The headbox according toclaim 1, wherein individual ones of said plurality of ribs have a ribthickness in a range of 20 mm to 50 mm.
 11. The headbox according toclaim 1, wherein individual ones of said plurality of ribs have a ribseparation in a range of 100 mm to 500 mm.
 12. The headbox according toclaim 1, wherein individual ones of said plurality of ribs have a ribseparation in a range of 125 mm to 400 mm.
 13. The headbox according toclaim 1, wherein individual ones of said plurality of ribs have a ribseparation in a range of 150 mm to 250 mm.
 14. The headbox according toclaim 1, wherein said table leaf of said central assembly includes afirst region facing said lower lip plate, said table leaf in said firstregion facing said lower lip plate including a first chamfer forming afirst bevel, said first chamfer having a first length of at least 25 mm.15. The headbox according to claim 14, wherein said lower lip plate is alower lip support plate.
 16. The headbox according to claim 14, whereinsaid first length is at least 40 mm.
 17. The headbox according to claim14, wherein said first length is at least 50 mm.
 18. The headboxaccording to claim 14, wherein said lower lip plate includes a secondregion facing said table leaf of said central assembly, said lower lipplate including a second chamfer forming a second bevel in said secondregion facing said table leaf of said central assembly, said secondchamfer having a second length of at least 25 mm.
 19. The headboxaccording to claim 18, wherein said lower lip plate is a lower lipsupport plate.
 20. The headbox according to claim 18, wherein saidsecond length is at least 40 mm.
 21. The headbox according to claim 18,wherein said second length is at least 50 mm.
 22. The headbox accordingto claim 18, wherein said first bevel and said second bevel formedrespectively by said first chamfer and said second chamfer encompasstogether an angle of 0 to 45°.
 23. The headbox according to claim 22,wherein said angle is 5 to 30°.
 24. The headbox according to claim 22,wherein said angle is 10 to 20°.
 25. The headbox according to claim 22,wherein individual ones of said plurality of ribs which connect saidlower lip plate with said table leaf of said central assembly arestructured to fill in in said first region and said second regionrespectively of said first chamfer and said second chamfer.
 26. Theheadbox according to claim 25, wherein said lower lip plate is a lowerlip support plate.
 27. The headbox according to claim 1, wherein saidtable leaf of said central assembly and said lower lip plate have aperpendicular distance in a first range of 10 mm to 100 mm, saidperpendicular distance being measured between a theoretic insideextension of said table leaf of said central assembly and a theoreticcorner edge of said lower lip plate.
 28. The headbox according to claim27, wherein said lower lip plate is a lower lip support plate.
 29. Theheadbox according to claim 27, wherein said first range is 20 mm to 80mm.
 30. The headbox according to claim 27, wherein said first range is25 mm to 65 mm.
 31. The headbox according to claim 27, wherein a minimumheight of individual ones of said plurality of ribs between said tableleaf of said central assembly and said lower lip plate assumes a valuein a second range of 1.5 to 4 times said perpendicular distance betweensaid table leaf of said central assembly and said lower lip plate. 32.The headbox according to claim 31, wherein said lower lip plate is alower lip support plate.
 33. The headbox according to claim 31, whereinsaid second range is 2 to 3 times said perpendicular distance betweensaid table leaf of said central assembly and said lower lip plate. 34.The headbox according to claim 1, wherein said table leaf includes afront side, individual ones of said plurality of ribs including a regionfacing said front side of said table leaf and a compensating gap in saidregion facing said front side of said table leaf, each respective saidcompensating gap having a height in a range of 2 mm to 15 mm.
 35. Theheadbox according to claim 34, wherein said range is 3 mm to 12 mm. 36.The headbox according to claim 34, wherein said range is 5 mm to 10 mm.37. The headbox according to claim 1, wherein a plurality of joints atleast one of (a) between said table leaf of said central assembly andrespectively individual ones of said plurality of ribs and (b) betweensaid lower lip plate and respectively said individual ones of saidplurality of ribs which are formed as a plurality of welding seams havea welding seam thickness in a range of 3 to 15 mm.
 38. The headboxaccording to claim 37, wherein said lower lip plate is a lower lipsupport plate.
 39. The headbox according to claim 37, wherein said rangeis 4 mm to 12 mm.
 40. The headbox according to claim 37, wherein saidrange is 5 mm to 10 mm.
 41. The headbox according to claim 1, whereinindividual ones of said plurality of ribs respectively are connected oneof directly and indirectly by at least one hinged joint and at least oneof a base plate and a pedestal with a bed plate.
 42. A machine toproduce a web of fibrous material from at least one fibrous stocksuspension, the web being one of a paper web, a cardboard web, and atissue web, said machine comprising: at least one headbox including: acentral assembly including a bottom side and having a table leaf on saidbottom side; a plurality of ribs; and a headbox nozzle adjoining saidcentral assembly directly downstream in a machine direction andextending in a cross machine direction, said headbox nozzle including atleast one continuous lower nozzle wall and at least one continuous uppernozzle wall extending across a machine width, said at least onecontinuous lower nozzle wall of said headbox nozzle including a lowerlip plate which is connected to said table leaf of said central assemblyby way of said plurality of ribs extending in said machine direction andspaced apart in said cross machine direction, said plurality of ribsbeing one of pliable and flexible in said cross machine direction. 43.The machine according to claim 42, further including a turbulencegenerator, said central assembly forming a plurality of carrier elementsof said turbulence generator.
 44. The machine according to claim 42,wherein said lower lip plate is welded to said table leaf.
 45. Themachine according to claim 42, wherein said lower lip plate is a lowerlip support plate.